1. Field of the Invention
Embodiments of the present invention relate to nacelle or pylon control for tiltrotor aircraft. More particularly, embodiments of the present invention relate to systems and methods for monitoring the positions of two nacelles or pylons on either side of a wing of a tiltrotor aircraft and preventing the two nacelles or pylons from going to significantly different positions than their commanded positions in the event that either one cannot be moved, or cannot be moved fast enough.
2. Background Information
A tiltrotor aircraft is generally an aircraft that can fly like a helicopter or like a propellered airplane, depending on the position of its rotors. A tiltrotor aircraft typically has at least one wing and at least two rotors located at either end of the wing. Each rotor is connected to a pod and each pod is, in turn, connected to the wing.
The pods are used to position each rotor relative to the wing. A pod that encloses one or more engines powering the rotor connected to the pod and positions the engine in addition to the rotor is called a nacelle. A pod that does not contain an engine powering the rotor connected to the pod is called a pylon. The term “pylon” is hereinafter used to refer to a pod, a nacelle, or a pylon.
A tiltrotor aircraft can be flown like a helicopter by generally positioning the pylons of the aircraft relative to the wing so that the rotors rotate about a generally vertical axis and in a horizontal plane. A tiltrotor can be flown like a propellered airplane by generally positioning the pylons of the aircraft so that the rotors rotate about a horizontal axis and in a vertical plane. The process of changing the position of the pylons of a tiltrotor aircraft between the vertical position (helicopter mode) and the horizontal position (airplane mode) during flight is called conversion. During conversion the two pylons on either side of a wing of a tiltrotor aircraft should not have significantly different positions than the commanded positions or move at significantly different rates than the commanded rates.
In view of the foregoing, it can be appreciated that a need exists for systems and methods that monitor the positions of two pylons on either side of a wing of a tiltrotor aircraft and the commanded positions of two pylons on either side of a wing of a tiltrotor aircraft and prevent the two pylons from going to significantly different positions than the commanded positions.